Steam generator



March 24, 1953 R. R. WATERMAN 2,632,572

STEAM GENERATOR Filed Nov. 15, 1949 28 22 27 F 15 E INVENTOR.

/ Passe/l 2. Vla/erman BY r A T TORNE' Y5 Patented Mar. 24, 1953 UNITED STATES ATENT OFFICE 6 Claims.

This invention relates generally to steam gen erator units of the type suitable for steam cleaning purposes.

In the past low pressure steam generating units have been used for steam cleaning operations on machinery parts, automotive engines, truck and automobile bodies, building walls and the like. For such operations it is desirable to provide relatively wet steam at low pressure, as for example steam which may have a quality of from to at a pressure which may be only a few pounds above atmospheric. One of the requirements of such a steam generating unit is that its normal operating periods are interrupted by periods of shutdown during which it is desirable to maintain the burner fire and to keep the boiler in steam generating condition. In order to facilitate such changes in operating conditions it is desirable to provide automatic means for controlling the feed water and fuel supply. When it is attempted to accomplish such automatic operation by conventional types of controlling equipment, the unit becomes relatively expensive and complicated to operate and maintain.

It is an object of the present invention to provide a steam generating unit and method which is particularly adapted for-steam cleaning operations, and which affords automatic control with a minimum of equipment and difiiculty.

Another object of the invention is to provide a steam cleaning unit and method which is characterized by the fact that it effects control in accordance with the quality of the steam supplied to the final discharge nozzle.

Another object of the invention is to provide a novel steam cleaning unit and method of the above character having provision enablin an operator to change the quality of the steam supplied to the final cleaner nozzle, without interfering with the desired automatic control.

Additional objects of the invention will appear from the following description in which the preferred embodiments of the invention have been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure l is a side elevational view schematically illustrating a steam generating unit incorporating the present invention.

Figure 2 is a cross-sectional detail illustrating the construction of the discharge nozzle incorporated in Figure 1.

Figure 3 is a schematic view like Figure 1, but illustrating anotherembodiment of the invention.

In Figure 1 of the drawing a tank I provided for containing a quantity of liquid 2. The liquid is maintained at a predetermined level by means of a flow control valve 3, which is connected to the water supply pipe 4,

In order to facilitate addition of a cleaning compound to the water in tank I, I provide a receptacle 5 located on top of the tank I, and adapted to contain a liquid 6 consisting of a dissolved or soluble cleaning compound. A small drip cock I is mounted on the receptacle 5 and is connected to a strainer pipe 8, within the receptacle 5. The drip cock discharges cleaning compound into the open ended pipe 9, which extends into the receptacle I below the normal water level.

The boiler unit is of the flash type and consists of a shell I0, having a stack outlet I I. A coil I2 of tubing is arranged within the shell III, and is heated by suitable means such as a gas burner I3. This burner is connected to the gas supply pipe I4, which is provided with a pressure operated control valve I5.

In order to supply feed water to the coil I2, I provide a steam driven feed water unit I6, which includes the steam driven prime mover IT, and the water pump I8. Both the prime mover and the pump are preferably of the positive displacement type.

The water supply pipe I9 connects the tank I to the inlet side of the pump I8. A pipe 20 connects from the discharge side of the pump I8 to the inlet end of the coil I2. A pipe 2i connects from the discharge side of the steam generating coil I2 to the so-called cleaning gun 22, which is used by the operator to supply steam where desired. A safety relief valve 23 and a pressure gauge 24 are shown connected to the pipe 2!. A pipe 25 connects between pipe 2! and the prime mover I I. Interposed in the pipe 25 there is a restricted flow control orifice 26. As will be presently explained fluid supplied through the conduit 25 and orifice 26 serves to operate the prime mover II.

The gun 22 includes the nozzle tip 21, and a pipe 28 which connects this tip to the hand operated valve 29. The hose 32 connects the gun to the steam supply pipe 2 I.

The nozzle tip 21 can be constructed as illustrated in Figure 2. Thus the end of the tip is provided with a Venturi shaped discharge orifice 3|, and also with a flow control orifice 32, which is separated from orifice 3 I by the chamber 33. As will be presently explained the proportioning of these orifices is such that when the manual valve 29 is in open position the amount of steam supplied is well within the capacity of the unit. In

3 addition the proportioning of these orifices i correlated with the size of the restriction 29, and the operation of the prime mover ll, as will be presently explained.

A pipe 34 connects with the exhaust side of the prime mover I7, and extends into the tank to a point above the liquid level. Steam and hot Water supplied through the pipe 34 serve to heat the liquid in the tank, and also serve to cause thermal circulation for intermixing the Water with the cleaning compound. Steam from the upper part of the tank I is bled through the pipe 35 to the upper part of the shell H), for discharge with gaseous products of combustion.

The pressure operated valve |5, in the gas supply line M, has a pressure pipe connection 33 with the steam pipe 2|. A valve controlled pipe 36a is connected to the outlet side of pump |8, and facilitates manual controlled blow down of water from the boiler.

A pipe 31, provided with a valve 38 connects between pipes 20 and 2|. The point of connection with pipe 2| is beyond the point of connection for pipe 25.

Operation of the steam generating unit described above, and the carrying out of my method, can be described as follows: It is assumed that water is in the tank I to the level indicated, and. that this level is being maintained by operation of the float valve 3. The drip valve 1 has been adjusted to permit cleaning compound to drip into the pipe 9, to be thereby introduced into the water in tank Also it is assumed that the steam generating unit is in operating condition, and that fuel gas is being supplied to the burner |3 for heating the coil i2. With the valve 29 open, and the gun 22 in use, relativel; wet steam is supplied to the gun 2 2 and discharged from the Venturi orifice 3|. A portion of the wet steam supplied from the boiler flows through the pipe line 25 and the orifice 26, to operate the prime mover H. The prime mover drives the pump l8 to supply feed water to the coil l2, at a rate commensurate with the rate of steam generation a d consumption. For given operating conditions, the rate of operation of the prime mover I! can be adjusted by changing the size of the orifice 26. Normally the orifice size is fixed whereby for a given size of orifices 3| and 32, the pump will be driven at a proper rate to supply the requisite amount of water to the coil l2, to continue operation for an extended period of time with the valve 29 open. Any rise in boiler pressure acts through pipe 36 to control valve l and thereby reduce the gas now to the burner. This tends to maintain the boiler pressure between desired limits.

With operation as described above the quality of steam supplied to the gun 2-2 will be of the order of 20 to 40%. For most steam cleaning operations of the type previously mentioned, it is desirable to provide wetter steam from the gun having a quality of say from 10 to With my invention such wet steam ca b? pro- Vided by the simple expedient oi opening the valve 38, to permit some hot water from the pump iii to pass directly into the pipe 2|. This water is intermixed with the steam, t e mixing operation being augmented by the action of the orifice 32 and chamber 33. Thus the discharge from the Venturi orifice 3| is a relatively homogeneous mixed phase material, consisting of droplets of hot water and vapor.

Assuming now that the operator wishes to shut down the gun temporarily, the valve 29 is closed, to stop further discharge of steam. This causes a slight increase in pressure in pipe 2|, whereby the valve i5 is operated to greatly reduce the supply of gas to the burner i3. Continued operation of the pump l8 after the valve 29 is closed serves to continue discharge of water through both the pipes 29 and 37, but this water now flows through the pipe 25 together with steam from the boiler. This results in a virtual flooding of the orifice 26 with water, whereby the amount of fluid flowing through the orifice 26 to the prime mover I? is greatly reduced. Under such conditions the prime mover ii is operated only at a relatively slow rate, sufficient to supply a minimum rate of feed water to the boiler unit for standby operation.

When the control valve 29 of the gun .22 is opened, after standby operations, steam is again supplied through the pipe 2| and hose 39, and the water flowing through pipe 3? is again intermixed with the steam and discharged from the tip 2'5. Steam at the quality being discharged from the outlet of the coil i2 is again supplied through pipe 25 and orifice 29 for operation of the prime mover i7.

In the foregoing explanation it is assumed that the valve 29 is either full open or closed. In addition my invention automatically compensates for variations in the rate of steam discharged from the gun 22. Thus if the valve 29 is turned to an intermediate position, to reduce the ficw of steam from the rate for full open position, the prime mover i'i initially continues operation without reduction in speed, and as a result the feed water pump ls supplies water to the coil |2 at a rate greater than that required for the reduced steam consumption. Within a short interval of time this causes a substantial reduction in the quality of steam supplied through pipe 2|, and because of the higher gravity of this steam, the amount supplied through the orifice 26 is effectively reduced to reduce the speed of operation of the prime mover l'l. When the speed of operation of the prime mover ll has been reduced to such a value that pump it operates at a speed commensurate with the reduced steam consumption, then the quality of steam in pipe 2| thereafter remains substantially constant.

As previously stated in a typical steam generating unit incorporating the present invention, the quality of the steam delivered through the pipe 2| will range from say 20 to 40%. This range of steam quality is ample for automatically controlling the operation of the prime mover ll. Such automatic control occurs not only in response to changes in the steam consumption, but also during normal operation to maintain proper stability whereby for a given setting of valve 29 the steam quality tends to be maintained constant. Thus if for a given setting of valve 29 the steam tends to increase in quality more steam flows through the orifice 26 to increase the rate of operation of pump is. This increases the rate of feed water supply which has a compensating effect in that it tends to decrease the quality of the steam.

In that embodiment of the invention shown in Figure 3, a pipe 2 a connects with the discharge end of the coil l2, and supplies steam directly to the prime mover l7. Pipe 39 connects with the exhaust side of the prime mover H and supplies steam to the hose 30 of the gun 22. A pipe 49 connects with the pipe 39, and leads into the tank I to terminate above the water level as indicated. This pipe is provided with the flow control orifice 4| and hand valve 42. Another pipe 43 has its one end connecting with the pipe 29 from the water pump i8, and its other end connecting with pipe 39 at a point beyond the point of connection of the latter with pipe 49.

The unit illustrated in Figure 3 operates as follows: When the'valve 29 is open wet steam is supplied from the boiler through pipe 2| a, through the prime mover IT, and through the pipe 39 and hose 39 to the gun 22. Assuming that valve 42 is open some steam is bypassed from the pipe 39 through pipe 49 and orifice 4|, to the interior of the tank I to heat the liquid therein. Assuming that valve 44 has been opened water is supplied through the pipe line 43 to the pipe 39 to intermingle with the boiler steam and to provide a relatively wet steam for the gun 22. When the valve 29 is closed normal flow of steam through the prime mover is arrested, but a small flow continues to occur through the pipe 40 and orifice 4|, into the interior of the tank I. In addition some water continues to flow through the pipe 43, and this water flows back through the pipe 39 into the pipe 49, to substantially flood the orifice 4|. As a result under such conditions flow through the orifice 4! is greatly reduced, and therefore flow through the prime mover I1 is reduced to a relatively low value sufiioient to operate the prime mover to in turn operate the pump H3 at a rate consistent with standby conditions. Immediately after valve 29 is opened, normal steam flow is re-established through the pipe 39, and thus steam flow is established through pipe 40 and orifice 4 I.

It will be evident that with the unit of Figure 3 the prime mover I! will be operated at a rate depending upon the rate of flow of steam through the same, and this in turn is determined by the steam consumption of gun 22. Likewise with this arrangement when steam consumption is interrupted, the unit automatically assumes standby operation, with the prime mover and pump operating at a minimum rate sufiicient to supply a small amount of water to the boiler coil to keep the unit in proper condition for immediately resuming normal steam generation. As is the case with the embodiment of Figure 1, the flame of the burner I3 is at all times maintained at a value consistent with the boiler pressure. Should the boiler pressure tend to rise the supply of gas is reduced.

This application is a continuation-in-part of my copending application Serial No. 654,781 filed March 15, 1946, now abandoned, and entitled Steam Cleaner Unit.

I claim:

1. A method for the generation of wet steam, the method making use of a wet steam boiler, a feed water pump connected to deliver feed Water to the boiler, and a prime mover adapted to be operated by steam and connected to drive the pump; the method comprising operating the boiler to deliver wet steam therefrom, causing a portion of the wet steam delivered from the boiler to flow through a restricted orifice for controlled operation of the prime mover, supplying hot water to the steam being consumed from the boiler, and causing such hot water to flood such orifice during periods when steam consumption is interrupted.

2. In a steam generator unit, a liquid feed water pump, a prime mover connected to drive the pump, a steam boiler, the liquid pump having its discharge connected to the boiler by a flow connecting means of constant flow passage characteristics, a delivery pipe connected to the outlet from said steam boiler to deliver wet steam to a point of steam consumption, a second pipe connecting the first named pipe with said prime mover, and a restricted orifice in said second named pipe forming the primary means therein to control the quantity of fluid supplied to the prime mover in inverse proportion to the wetness of the steam flowing therethrough, said prime mover having an exhaust means for discharge of fluid therefrom during intervals when the delivery pipe is closed.

3. In a steam generator unit, a liquid feed water pump, a prime mover connected to drive the pump, a steam boiler of the flash type, the pump having its discharge connected to the boiler by a flow connecting means of constant flow passage characteristics, a delivery pipe connected to the steam outlet of the boiler, a hose connected with said pipe, a steam applicator gun attached to the end of the hose, a second pipe connecting between said first named pipe and the inlet of the prime mover and serving to supply fluid to the prime mover for operation of the same, and a restricted orifice in said last named pipe forming the primary means therein to control the operation of the prime mover for either steam discharge or shutdown condition of the applicator gun, said prime mover having an exhaust means for discharge of fluid therefrom during intervals when the delivery pipe is closed.

4. In a steam generator unit of the type described, a boiler of th flash type, a liquid feed water pump, a pipe connecting the liquid discharge side of the pump to the inlet of the boiler and serving to supply feed water to the same, said pipe providing a substantially unrestricted flow passage of fixed flow characteristics, a prime mover adapted to be operated by steam and mechanically connected to operate the pump, said prime mover having an exhaust means for discharge of fluid therefrom during intervals when the delivery pipe is closed, a source of water supply connected to the inlet side of the pump, a steam pipe adapted to receive steam from the outlet end of the boiler, a hose connected to said steam pipe, an applicator gun connected to said hose and serving to apply steam where desired, another pipe connected to deliver water from the discharge side of said pump to said steam pipe for mixture with steam flowing through the same, and means serving to supply steam to the prime mover from the boiler unit for operation of the pump, said last means serving to supply fluid to said prime mover during periods of shutdown for relatively slow standby operation of the prime mover and pump.

5. In a steam generator unit of the type described, a boiler of the flash type, a feed water pump having its outlet side directly connected to the inlet of the boiler by a flow connection of fixed flow characteristics, a prime mover adapted to be operated by steam and directly connected to the pump, a source of water connected to the inlet side of the pump, a steam fiow delivery pipe connected to the outlet of the boiler unit, said prime mover having an exhaust means for discharge of fluid therefrom during intervals when the delivery pipe is closed, a hose connected to said pipe, a steam applicator gun connected to the end of the hose, a second pipe having its one end connected to said first named pipe and its other end connected to he inlet side of the prime mover, a flow restricting orifice in said second pipe, a third pipe having its one end connected to the discharge side of the pump and its other end connected to said steam flow pipe, said third pipe servin to supply water to the steam flow pipe for mixture with steam generated by the boiler, the point of connection between said third and steam flow pipes being on the downstream side with respect to th point of connection between he steam flow and the second named pipes.

6. In a steam generator of the type described, a boiler of the flash type, a feed water pump having its outlet side connected to the inlet of the boiler unit by a flow connection of fixed flow characteristics, a prim mover adapted to be operated by steam and mechanically connected to drive the pump, a first steam fiow pipe directly connecting the outlet of the boile to the inlet of the prime mover, a second pipe connected to the outlet Of the prime mover and serving to deliver all of the boiler steam to a point of steam demand, a, liquid tank for supplying water to the pump, a third pipe connected to said second pipe and extendin into said tank for heating the Water therein, a flow restricting orifice in said last named pipe, said orifice forming the primary means for controlling the quantity of fluid supplied to the prime mover, and a fourth pipe having one end of the same connected to th discharge side of said pump and its other end connected to said second named pipe, said last named pip serving to supply hot water from the pump to said second named pipe for mixture with steam flowing through the same, the point of connection between said fourth and second mentioned pipes being beyond the point of connection between the second and third pipes.

EUSSEIL R. WATERMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 743,661 Rice Nov. 10, 1903 1,766,088 Wier June 24, 1930 2,044,557 Alvert June 16, 1936 2,077,257 Ofeldt Apr. 13, 1937 2,128,263 Ofeldt Aug. 30, 1938 2,345,614 Malsbary et a1. Apr. 4, 1944 2,350,876 Clarkson June 6, 1944 2,355,125 Waterman Aug. 8, 1944 2,396,032 Waterman Mar. 5, 1946 

